The present invention pertains to a process for separating an electrodeposited metal from a cathode plate in electrolytic refining, and to an apparatus specifically adapted to carry out the same process.
A conventional electrolytic refining process involves preparing as a cathode plate a starter sheet of the same metal as the target metal to be refined, and carrying out electrolytic refining by electrodepositing the metal to be refined on the cathode plate. Subsequently, the electrodeposited metal is melted together with the starter sheet, and cast into an ingot.
In the above process, however, a starter sheet must be prepared every time electrolytic refining is carried out. Furthermore, it is necessary to secure a suspension bar of a conductive material to the starter sheet in order to hold the sheet in an electrolytic cell and apply electric current to the sheet, and much workload is required for the securing task because the starter sheets to be accommodated in a single electrolytic cell reach a considerable number.
In order to circumvent the above disadvantages, a modified electrolytic refining process has been proposed as disclosed in Japanese Patent Application, B-Publication Number 59-43996 or Japanese Patent Application, B-Publication Number 63-42716. In this process, a mother blank formed of stainless steel or titanium is used, and the metal to be refined is electrodeposited thereon. Then, the electrodeposited metal is mechanically separated from the mother blank, and the mother blank is repeatedly employed.
However, since the metal is electrodeposited on the entire outer surface of the mother blank including the edge portions, the task of separating the electrodeposited metal from the mother blank has been very laborious.
Furthermore, in order to facilitate the separation of the electrodeposited metal, another modified process has been proposed which includes covering the edge portions of the mother blank with an edge protector of an insulating material, and electrodepositing the metal only on the front and rear surfaces of the mother blank with electrodepositing the metal on the edge portions. With this modification, the mother blank can be used repeatedly, but when separating the metal from the mother blank mechanically, the mother blank may be subjected to deformation or damage, or the edge protector may be damaged. Thus, it has been necessary to repair or reform the mother blank and the protector.
Moreover, since tin, lead, indium or the like is less hard, it has been very difficult to separate it mechanically.